Forage can be stored either dried as hay or wet as silage. Silage is dominating because of the large dependency on the weather at hay-making. Silage is usually stored in either bales covered with plastic or in trench or tower silos. Silage is achieved by lactic acid creating bacteria, which are growing when the forage is stored air-tight and thus pH is decreased. Air-tightness and low pH prevents harmful bacteria, yeasts and moulds from destroying the forage. To help the process several additives for silage are present on the market. These additives are either lactic acid creating bacteria that compete with other microorganisms or chemicals that favour the growth of lactic acid creating bacteria and inhibit other microorganisms.
It is known that in order to make silage from forage plants that cannot be ensiled without difficulties, e.g. most green protein rich fodders or rain destroyed forage, it may be necessary to use controlling additive to prevent improper fermentation. The improved effect of ensiling agents results from a promotion of natural acidification. The thereby achieved drop in pH in the forage prevents the growth of harmful bacteria, yeast and mould, which can destroy forage by degradation. A family of bacteria being responsible for undesirable degradation of forage nutrients such as sugars and proteins is Clostridia. The predominant Clostridium species is Clostridium tyrobutyricum, but also other Clostridium species may be present in forage or silage. Furthermore, the quality of the forage is of great importance for animal health since forage of low quality has a negative impact on the animals immune defense and make them more susceptible for infections. The use of ensiling agents also affect products coming from the animals, such as milk and other dairy products. Thus ensiling agents of the highest possible quality is preferred. By using ensiling agents on forage increased storage stability, as well as an increased stability of the opened forage, may be achieved.
Ensiling agents comprising chemical compounds favour the development and growth of lactic acid producing bacteria and inhibit other microorganisms. An ensiling agent available on the market is Promyr NF that is marketed by Perstorp Speciality Chemicals AB. Promyr NF is an acidic composition containing formic acid and propionic acid and salts of organic acids, such as sodium formiate. Due to its acidity Promyr NF lowers the pH of the forage rapidly. Promyr NF has low stability when the forage is exposed to air, which implies that the forage is degraded upon opening. Thereby, forage of lower quality may be given to the animals. This low stability upon opening is especially valid for forages having a high DM and typically for forages with a DM of 40-60%. In addition, Promyr NF is corrosive and therefore to a large extent damages the equipment and machines that are in contact with the ensilage. Promyr NF only relies on its low pH as a protection against Clostridia, there are no additional components which hinders the growth of Clostridia. Upon opening of the silage Promyr NF does not confer any additional protection against fungus and mould. Another known ensiling agent is marketed as Kofasil Ultra and it is produced by ADDCON GROUP GmbH. Kofasil Ultra contains sodium benzoate, sodium nitrite, hexamine (hexamethylenetetramine) and sodium propionate. Lingvall and Lättemäe (Lingvall P & Lättemäe P (1999) Journal of the Science of Food and Agriculture. 79: p. 257-264) disclose different silage additives comprising hexamine, sodium nitrite, sodium benzoate and sodium propionate in different combinations, and Kofasil Ultra is disclosed but not referred to by name. A problem with Kofasil Ultra is that it contains hexamine, which may lead to toxic degradation products. The effect of hexamine is assumed to arise from the fact that formaldehyde is split off during the fermentation period. Hexamine may give rise to allergic reactions and therefore Kofasil Ultra is marked as having a potential allergic effect. Besides possible toxic side effects a disadvantage with hexamine is decomposition during the fermentation process, especially in the maturing phase of fermentation (U.S. Pat. No. 4,088,789). Although the concentration of hexamine could be decreased when being used in combination with benzoates in ensiling agents (U.S. Pat. No. 4,088,789) the problems of possible toxicity and its degradation to formaldehyde still remain. Another disadvantage is the rather high sodium nitrite concentration in Kofasil Ultra, which may be toxic for animals. One additional disadvantage is that Kofasil Ultra requires a 4 week waiting period before using the silage.